Its no secret the Allison OE C2 hub lacks in durability. TCS addressed this failure area with their billet c2 hub upgrade. DHD recommends this upgrade on any build over 750hp as well as trucks used for pulling, drag racing or boosted launches.
4140 HTSR Billet Steel
+.125" More Shaft Spline Contact
+.100" Spline Boss Diameter
Added clutch spline length to accommodate 1 additional clutch friction